other looking them up manually, all i can think of is to
1. purchase a list (search internet) which may include some of the comapnies-a CFO trade organization might be a good start (e..g National Assoc. of CFO’s). If they have (most do) regular conferences, sometimes the attendees are published on the conference website. Would take a lot of web research but might pan out.

2. depending on how geographically dispersed they are (if many are located in the same area), perhaps local business orgs., chamber of commerce, etc. would have some info.

Tough issue-lots of luck.